A police officer has been disciplined after a complaints watchdog found he did "virtually nothing" for almost a year to investigate a serious assault on a schoolboy.

The Police Ombudsman for Northern Ireland recommended the disciplinary action after investigating a complaint made by the boy's mother.

Ombudsman investigators found the officer made some initial inquiries but then "failed to progress the case in any significant way for 10 months".

The watchdog said the officer could provide "no valid reason" for his inaction.

In the wake of the 2014 assault, which left the Co Down schoolboy with a broken front tooth, a suspected broken wrist, a black eye and bruising, his mother made repeated attempts to contact the investigating officer, with no success.

She told the Ombudsman she tried the number he had given her, and left a message, but received no reply.

She later tried to contact him via the PSNI's non-emergency 101 number, which she called three times.

The woman still received no response, despite the call handler advising during the third call that the officer's sergeant would be informed.

Only once during this 10-month period did she manage to speak to the officer. That was when he returned a call after she learned that he had failed to submit paperwork relating to the case.

When questioned about the complaint, the officer said he had been busy with a number of other cases and had, on occasions, been extracted from his investigative role to perform other duties.

He also claimed he had forgotten the password for his answerphone and had not used that number for a long time. However, he did accept he had received one message which he failed to reply to.

A Police Ombudsman investigator said it was "unacceptable" that the officer had provided the boy's mother with a contact number he did not use.

When asked why it had taken almost a year for him to secure consent to access the boy's medical and dental records, the officer said he had forgotten about it. He also admitted incorrectly dating a statement taken from the boy.

The Ombudsman's office said the PSNI had implemented a recommendation to discipline the officer.